62 lines
1.2 KiB
C
62 lines
1.2 KiB
C
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/*
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* Control PB5 with the two buttons. One button disables, the other enables.
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* The board uses interrupts for this. PB5 will quickly oscilate between on and
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* off to make cool sounds with a summer.
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*/
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#define F_CPU 16000000UL
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#define __AVR_ATmega328P__
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include <util/delay.h>
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#define MINUTE 60 * 1000
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const int TIME = 45 * MINUTE;
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int volatile reset = 0;
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int alarm();
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// code for INT0
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ISR(INT0_vect) { reset = 1; }
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int main(void) {
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DDRB = 0xff; // write to B
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DDRD = 0; // read from D
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PORTD |= (1 << PORTD2) | (1 << PORTD3); // pull up D2 and D3
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PORTB = 0; // pull down port B
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// enable external interruprs
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EIMSK |= (1 << INT0);
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EIMSK |= (1 << INT1);
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// trigger when anything changes
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EICRA |= (1 << ISC00); // for INT0
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EICRA |= (1 << ISC10); // for INT1
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sei(); // interrupt magic macro
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while (1) {
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_delay_ms(TIME);
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alarm();
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}
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}
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int alarm(void) {
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int sound = 0;
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while (!reset) {
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PORTB |= (1 << PORTB5);
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_delay_us(sound);
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PORTB &= ~(1 << PORTB5);
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_delay_us(sound);
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sound++;
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if (sound > 1000) {
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sound = 0;
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}
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}
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reset = 0;
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PORTB &= ~(1 << PORTB5);
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return 0;
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}
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